The central figure of the medieval church died almost half a millennium before the date usually given for the beginning of the Middle Ages. Enigmatic as it may sound, Christ was born Before Christ. When in the sixth century Dionysius Exiguus used the birth of Christ to date the beginning of the Christian era, he mistakenly believed that Christ was born in the Roman year 754 ab urbe condita (‘from the founding of the city’), and that year is called the first year of the Christian era: AD 1. In fact, King Herod, during whose reign Christ was born, died in the Roman year 750, and the date given by modern scholars for Christ’s birth generally falls between 8 and 4 BC. The date of Christ’s death – and, indeed, his age at the time of his death – are not known for certain, but he was probably executed in the year AD 30.

To some of his fellow Jews Jesus of Nazareth was the long-awaited Messiah, the fulfilment of the prophecies, the saviour of his people, the expected of the nations. They believed he was born of a virgin, whose cult was to become a significant feature of medieval religious life. They heard him preach not a new law but the fulfilment of the Jewish law, summarized in the Sermon on the Mount (Matthew, chs 5–6) in a doctrine of universal love: not an eye for an eye and a tooth for a tooth (lex talionis), but ‘turn the other cheek’, ‘love your enemies and pray for your persecutors’. When asked how to pray, he told them to say, ‘Our Father, who art in heaven’ and gave the world the central prayer of the Christian faith. The political problems that he posed for the rabbinical leaders and for the Roman authorities led to his execution by crucifixion on a hill outside Jerusalem between two thieves. His followers were strongly motivated by the conviction that he had actually risen from the dead three days after his death. Many said that they saw him during the next forty days and that then on the fortieth day that they saw him ascend bodily into heaven. Huddled together in fear and confusion ten days later, his followers were said to have been inspired by the Holy Spirit under the appearance of tongues of fire.

They believed that the human race had fallen by reason of the sins of Adam and Eve, the consequences of which affected all peoples. To redeem mankind from this sin God sent his Son to earth in the form of a human being, whose death on the cross was a redemptive sacrifice for the whole human race. Christ, the God–man, was redeemer, saviour, reconciler; it was through belief in him that salvation – a heavenly life in the next world – was to come. This was the message his followers were to preach.

The apostolic church

The band of twelve, the place of Judas the suicide now taken by Matthias, plus several scores of disciples and a loyal band of holy women – a scant 100 or so in total – formed the core group from which the Christian church was to grow. They had been given no master plan, no blueprint, for an institution, merely the mandate to preach the good news (gospel) to all peoples, baptizing them in the name of the Father, Son and Holy Spirit (Matthew 28, 19; Mark 16, 15; Acts 1, 8). The pages of the Acts of the Apostles tell in detail the story of the infant church or, more accurately, the story of the growth of this small band of Jewish followers of Christ to a movement. The author of Acts (probably the evangelist Luke) with unconcealed pleasure quotes the learned rabbi Gamaliel: ‘If this idea of theirs or its execution is of human origin, it will collapse; but if it is from God, you will never be able to put them down’ (5, 38–39). This band of early Christians was comprised of Jews, who viewed themselves as part of the Jewish religious tradition: we would say that they formed a sect of Judaism. They soon made a decision of monumental historical significance.

The question they asked themselves was: should gentile converts be compelled to undergo circumcision (the Jewish rite of initiation) and become subject to the dietary and other obligations of Judaism? At what has been anachronistically called the ‘Council’ of Jerusalem (AD 49 or 50) this issue was discussed, and the assembled group of Christian leaders endorsed the opinion of Peter: gentiles need not first become religious Jews. This decision opened the way to the conversion of non-Jews, its significance impossible to exaggerate. Tradition has traced apostles to far-flung parts of the world. Christians of south India trace their Christianity back to the apostle Thomas, who they believe is buried near Madras. John was believed to have been at the city of Ephesus in Asia Minor (Efes in modern Turkey). Matthew may have been active in Ethiopia. Pilgrims still climb mountain passes to the legendary burial place of the apostle James at Compostela in northern Spain. On the historical side of tradition and legend we see the figure of the ‘apostle of the gentiles’, Paul, the persecutor who was struck down on the road to Damascus and rose as the missionary par excellence. He has been well served by Luke, who, in great detail in Acts, describes the missionary journeys of Paul through the Mediterranean world. Etched in the consciousness of peoples for centuries to come was Luke’s picture of this learned Jew, Paul, in the agora at Athens, where Socrates had spoken four centuries earlier, and also the picture of him talking to men of wisdom on the Areopagus hill below the Acropolis.

Men of Athens, I see that in everything that concerns religion you are uncommonly scrupulous. For as I was going around looking at the objects of your worship I noticed among other things an altar bearing the inscription ‘To an Unknown God’. What you worship but do not know – that is what I proclaim.

(Acts 17, 22–23)

Paul, when later arrested, claimed his rights as a Roman citizen – he was from Tarsus – appealed to Caesar and arrived in Rome in chains.

Already at Rome there was a Christian community. Emperor Claudius c.AD 51 expelled Jews from the city because of trouble concerning a certain ‘Crestos’. It requires little historical imagination to see in this matter some discord within the Jewish community at Rome concerning the believers in Christ. When Paul arrived there (c.AD 60), Roman Christians, to whom he had already sent an epistle, welcomed him. The Roman historian Tacitus relates that in the year 64 Christians constituted a vast multitude (ingens multitudo), and, even if we allow here for exaggeration, it seems clear that by then they formed a definable group distinct from the Jewish community at Rome. That the apostle Peter was at Rome is undeniable and that he died during the persecution of Nero (64–67) seems more than likely. Excavations under St Peter’s Basilica have unearthed a shrine built in the second century on a slope of the Vatican, which may very well mark the spot of Peter’s burial. Also, it was from Rome that a tradition holds that Paul wrote to a follower the words,

Already my life is being poured out on the altar, and the hour for my departure is upon me: I have run the great race, I have finished the course, I have kept faith.

(2 Timothy 4, 6–7)

It is generally believed that, like Peter, Paul too perished in the Neronian persecution, and there is a fairly early tradition that his body lies beneath the church of St Paul’s-Without-the-Walls. What is historically certain is that Peter and Paul both died at Rome and a fairly early tradition links them as ‘founders’ of the Roman church, the Christian Romulus and Remus, as it were.

The spread of Christianity

How to explain the rapid growth of Christianity from the small band of Jews in Jerusalem to the dominant religion of the Roman Empire, which it was to become? Some may perceive in all this the workings of a divine providence, but the historian as historian lacks that kind of vision and, by definition, can and should only see the workings of human agents and natural forces. Over two centuries ago Edward Gibbon, writing probably with a considerable measure of irony, asked, ‘What were the secondary causes of the rapid growth of Christianity?’ (Decline and Fall, chapter 15). Modern historians eschew ‘causes’ and discuss ‘factors’: what factors contributed to the growth of Christianity? Two will be singled out here: the existence of the Roman Empire and a spiritual vacuum in the Roman world.

It would be difficult to exaggerate the significance of the where and when of the birth of the Christian religion: Jesus was born in the Roman Empire, albeit at a remote edge of that empire. The Romans under Pompey had conquered Palestine in 63 BC, and at once this tiny land with an ancient people became part of a mighty empire which was to stretch from Scotland in the north to the Sahara in the south and from Spain in the west to Syria in the east. Jesus was born while Herod, a part-Jew, ruled as local king and Roman surrogate in Palestine. When asked about tribute in a trick question, Jesus replied to ‘render to Caesar the things that are Caesar’s … ’. He was executed while Pontius Pilate was the Roman procurator of Judea. A large diaspora of Jews lived outside Palestine in other parts of the Roman Empire: perhaps four million – four times the Jewish population of Palestine – in such cities as Alexandria, Ephesus, Antioch, Corinth and even Rome. Paul himself was from Tarsus, capital of Cilicia, in the south-eastern part of modern Turkey. He had a Greek name, Paul, and was a Roman citizen. No frontiers need be crossed within the Roman world. Roman engineers had constructed thousands of miles of roads, which, like modern railways, linked the remotest parts. And the Mediterranean Sea, as its name implies (‘the water in the midst of the land’), was an inland lake with Roman lands along all its shores. No wonder the Romans called it mare nostrum (‘our sea’). For 200 years a population of perhaps as many as 70 million people at a given time lived in a peace (Pax Romana) of a length seldom known in human history before or since. Although wars were fought at trouble spots along its long exterior borders and two rebellions were savagely put down in Judea and two brief civil wars occurred over the emperorship, the period was essentially one of a general, prolonged peace and extensive, if not universal, prosperity. Two languages – Greek and Latin – were linguistic equipment enough to allow one to travel with ease across the over two-thousand-mile east–west axis. Problems were to arise – and these will be visited shortly – but it is difficult to imagine more favourable circumstances for the spread of Christianity.

Map 1 Mediterranean region with early Christian sites

Favourale in another way was what we might call a spiritual void, a yearning for personal fulfilment of the inner person, a need largely unsatisfied by the formal state religion of Rome. Whatever appeal the cults of the ancient gods might have once had, by the first century they had become formalized festivities, like in our times the trooping of the colours by the monarch or Fourth-of-July parades and fireworks. They were largely civic and even patriotic events, which hardly brought meaning to the deeper parts of the human soul, where reside questions of the ultimate meaning of life. Some Romans found answers in the teachings of their Stoic philosophers, like Seneca, who saw virtue, not material success, as the path of wisdom leading to human happiness. Attractive in many ways, Stoicism appealed by and large to a small elite. Of wider appeal were the religions which entered the West from the more remote eastern parts of the Roman world and even beyond. Usually said to have been brought back by returning Roman legionaries, cults such as those to Mithras and Isis touched a responsive chord. For many the search for meaning went beyond the coolly rational teachings of the philosophers, and for them these mystery religions could have an appealing affective element. Men who pledged themselves to Mithras, the Persian sun god, were formally initiated, ate meals together, committed themselves to such manly virtues as loyalty and courage and held secret meetings in caves or cave-like places, and a happy life after death was promised to its votaries. Hundreds of shrines of Mithras, frequently showing a suffering Mithras, have been found throughout the Roman world: one of the most well known lies far beneath the church of San Clemente in Rome. Was Christianity but another Eastern mystery religion, similar in some ways to the cult of Mithras? Despite obvious points of external similarity, Christianity differed in essential ways from these other religions from the East. It alone was monotheistic. At its centre was not a mythological person but an actual historical person. A religion based on a rigid moral code, Christianity stood apart from the mystery cults, yet it tapped some of the same human yearnings. What was perceived as a high moral code – in Tertullian’s familiar phrase ‘See the Christians: how they love one another’ – provided a powerful attraction to souls in search of a religion which affected their whole lives.

With these favourable factors contributing, Christian communities were to be found by the end of the first century in every city of the empire, no longer submerged within the Jewish community. About the year 112 Pliny the Younger, once consul in Rome, wrote from Asia Minor that Christianity was reaching even into the villages. By the end of that century Christianity had reached remotest Britain. Numbers are difficult to come at in all this, but, by the conversion of Constantine in 312, perhaps as many as six or seven million Christians lived within the empire and an untold but no doubt smaller number beyond its borders. By any measure a remarkable achievement, perhaps unsurpassed in conversion history.

The persecutions: a historical problem

Few subjects in this process have exercised the talents of historians more than the significance of the persecution of the Christians by the Roman state. The facts are not really in dispute; it is their interpretation which divides their students. In 64 the emperor Nero singled out the nascent Christian community at Rome as a scapegoat for the burning of Rome. It was a local persecution, restricted to the city itself, and it lasted perhaps three years. What Nero did was to create a precedent that permitted the persecution of Christians as Christians. Clearer reasons for their persecution were in time to be enunciated: they were atheists in not worshipping the gods and traitors in not honouring the emperor as a god. For the next 200 years after Nero’s scapegoating, Christians were persecuted sporadically but only in specific locations – now at Alexandria, now at Smyrna, now at Rome, etc. – and never for a prolonged period in any of these. Even the seemingly benign Marcus Aurelius, whose Meditations continue to inspire thoughtful readers, in 177 sanctioned persecution, including the brutal executions of 48 Christians at Lyons: some strangled and beheaded, others given, while still living, to the wild beasts in the amphitheatre. A period of prolonged peace lasted from 211 to 250. Matters changed in 250 when Emperor Decius ordered all Christians to deny their Christian belief and to worship the Roman gods; those who refused paid with their lives. Continued by his successor, this total persecution finally ended in 260. The 40 years that followed saw a de facto toleration, even to the extent of Christians becoming provincial governors. The mightiest persecution – often called The Great Persecution – was the last: Diocletian moved against the Christians in 303 and in the following year decreed death to all Christians throughout the empire. Before this general persecution ended in 311, more Christians, it is said, were slaughtered than in all previous persecutions combined.

Some may see the Roman persecutions of the Christians as a main theme in the first three centuries of the Christian era, others see them at most as a minor theme. What is clear is that the picture of Christians in an ‘underground’ church, worshipping by stealth in the catacombs, being ruthlessly sought out by a uniformly hostile state and fed to lions is a picture hardly borne out by the facts. Sporadic and affecting only a very small number of Christians, the persecutions probably were not major negative forces in the process of the growth of the Christian religion. Yet throughout this period from the time of Nero to the conversion of Constantine (312) the Christian religion was not only officially proscribed but, perhaps more importantly, was the object of suspicion, hideous rumours and popular outbursts of ill-treatment. Not totally secure in the Roman state, the early Christians did not know when or where persecution or rioting might erupt against them. Also – and its weight defies measurement – the heroic and peaceful way in which many Christians received the ‘martyr’s crown’ attracted the admiration of pagans. Tertullian’s well-known epigram that the blood of martyrs acted as a seed for the growth of the Christian religion (semen est sanguis Christianorum) reflects the view that persecution merely strengthened Christianity. Still, it is fair to say that an overemphasis of the popular opposition and official persecutions probably distorts the historical realities.

Constantine, controversy and conversion

At the time of Constantine’s conversion (312) and the Edict of Milan (313) the Christians composed perhaps one-tenth or so of the population of the empire with a somewhat larger concentration in the East than in the West. While Constantine’s motives can be debated, the effect of his policy transformed the religious culture of the Roman world and was clearly a defining moment in the history of the church. Free now from persecution – a tolerated church (ecclesia tolerabilis) – the Christian religion prospered as it never had before. By the end of the century the majority of the people professed Christianity, which in 392, in effect, became the official religion of the Roman state.

From apostolic times the movement had some organization: the unit was the local church (ecclesia). The local community at Corinth was known as the church of Corinth, and so it was with the other local Christian communities. At each church some person presided; he was called by different names but has become known as ‘bishop’. He and his community welcomed new members in an initiation rite (baptism with water and affirmation of the Christian name). They worshipped together in private homes at a Eucharist (‘thanksgiving’) that memorialized the Last Supper of Christ with his apostles. By the time of Constantine the ‘bishops’ of the great churches at Antioch, Alexandria and Rome exercised authority beyond their local churches. Constantine’s establishment of a ‘new Rome’ on the Bosporus at the small port of Byzantium, to which he gave his own name, meant that Constantinople would take its place with these three and would play a prominent part in church affairs.

The emergence of Christianity into the full light of day provided the opportunity and, indeed, the necessity for Christians to reflect on the nature of their religion. The New Testament provided inspirational reading but not an organized body of Christian theology. Differences soon emerged and focused on the central issue of the Christian religion: the nature of Christ. The gospels declared that he was the Messiah, the fulfilment of the prophecies, the redeemer of mankind, the expectation of the nations. But what was he? Was he merely a good and great man whose message of hope and love and the pre-eminence of the spirit touched the hearts of men and women? Or was he more? Did Jesus of Nazareth partake of the deity in some way? If so, how? Was the ‘Son of God’ really God? And if so, how could this be if there is only one God? Simply put, the two related issues which were to trouble Christianity in its long history were the divinity of Christ and the nature of the Godhead. The issues are obviously intertwined and go to the very heart of Christian belief.

In a moment of great theatre Emperor Constantine, in 325, took the place of pre-eminence at a council of bishops at Nicaea to resolve the dispute about the nature of Christ. A holy priest of Alexandria, Arius, had been teaching that there was a time when Christ was not, that God the Father created his son out of nothing (ex nihilo) and endowed his creature with extraordinary, divine-like powers. This was not Christ the God, but Christ the creature. Before the matter was officially resolved by this council at Nicaea and later councils at Constantinople (381) and Chalcedon (451), much of Christendom was riven into two camps over the issue of the divinity of Christ. In the fourth century, the debate centred on which Greek word accurately described the relationship of Christ to God the Father: was he of the same substance as the Father δm¨όυσιος (homo-ousios) or merely of like substance to the Father ó̔μοιύσιος (homoi-ousios)? Only the frivolous would scorn this as a debate over the Greek letter ι (iota): it was, in fact, a debate over whether Christ is God or only godlike. The creed developed by these councils, generally called the Nicene Creed and still used in the rites of Christian churches, asserts that Christ is God (i.e., ó̔μούσιoς, of the same substance as the Father). The Arians were defeated, but their teaching was to live on among many German tribes who were converted to Christianity in its Arian form. Subsequent debate centred on how Christ could be both the immutable God and the clearly mutable human. How could the Son of God become incarnate in time and place? What is the nature of this incarnate God (‘the Word made flesh’)? Are there two persons, one divine and one human? The councils, while leaving room for theological speculation, taught that Christ was one person who is fully God and fully human. Theologians were later to explain this union of the divine and human (the hypostatic union) by distinguishing between person and nature: they are metaphysically different and, hence, the person Christ could have two natures, one divine and one human.

A clearly related issue was apparent to all: if Jesus is God and is distinct from God the Father, why are there not two gods? how could Christianity escape from polytheism? And the matter was further involved by the belief that the Holy Spirit also is God and also is distinct from the Father and the Son. Monotheism was obviously at stake in this trinitarian debate. The Christian orthodoxy that emerged held to a Trinity: one God and three divine persons. It was later to be summed up in the Athanasian Creed:

Ita deus pater, deus filius, deus spiritus sanctus,
Et tamen non tres dii, sed unus est deus.

(Thus, God the Father, God the Son, God the Holy Spirit,
Yet not three gods but one God.)

Here, again, later theologians were to apply to this ‘mystery’ the same metaphysical distinction between person and nature: God can have one nature (divine) and three persons (Father, Son and Holy Spirit).

The fourth and fifth centuries witnessed more – much more – than doctrinal disputes. The very councils just mentioned attest to the fact that there was a sense of the church, the wider community of Christian believers, which was more than a collection of local churches: the whole being not only more but different from the sum of its parts. This sense of the Christian – authors by this time used the word ‘Catholic’ – church can also be seen in the body of Christian literature, from East and West, which was written not merely for the local church but for the whole body of Christian believers. If examples are only given here from the Latin West, it is because these became part of the medieval library. Augustine (354–430) was the greatest mind of his age and devoted much of his talents to writing theological works (e.g. De trinitate, On the Trinity), which became the subject of commentaries throughout the Middle Ages. His Confessions describes for the ages the story of the anguish of a soul in search of rest. In the City of God he presented a theological view of human history which still finds an audience. If Augustine was anguished, his contemporary Jerome (d. 420) was irascible. An often-repeated anecdote has a modern pope shaking his fist at a statue of St Jerome in the Vatican garden and saying ‘How did you become a saint?’ Yet, despite his irascibility, Jerome was to give the Middle Ages its greatest book, the translation of the Greek Bible into Latin, known historically as the Latin Vulgate. And completing the trinity of these Latin ‘Fathers of the Church’ is the urbane Ambrose (d. 397), Roman official who became bishop of Milan and humbled the emperor Theodosius the Great. His prose reflected the sonoritas of the prose of Cicero, whose De officiis (On Duties) Ambrose used as a model to write about Christian ethics. These great Fathers of the Latin church – to be joined later by Gregory the Great – were impelled by a sense of the church which transcended the merely local and provincial and which was the community of all believers.

One of the most remarkable events in world history has to be the conversion of the Roman Empire to Christianity, a process largely of the fourth century. Students of Roman history are used to a division of their subject into the Roman Republic and the Roman Empire. To these a third should be added, the Christian Roman Empire, which was clearly a part of ancient history. From a small minority in 312 Christians came to form the majority by at least the 380s. Christian churches were built in the basilica style. In Rome, St Paul’s-Without-the-Walls, built about 380 and rebuilt after a fire in 1823 to the original design, remains perhaps the best example of its type. By the end of the fourth century there were several thousand monks living in the desert outside Alexandria in Egypt. Even in distant Britain, Christianity had become firmly established. It had already, in the third century, had its first martyr, Alban, slain at Verulamium, and after Christian emancipation three bishops from Britain attended the church council held at Arles in 314, and bishops from Britain are known to have attended the council at Rimini in 359. Also, the remains of a Christian church at Silchester, a large cemetery at Dorchester and a hoard of Christian plate at Water Newton (Northamptonshire) attest to a large Christian community in Roman Britain. At the other end of the Roman world, a Christian community was being established in the lands below the Caucasus in Armenia, where Tiridates (d. 314), client king to the Roman emperor, was converted and his people soon followed. These examples could be multiplied. While the actual process of Christianization challenges precise definition and measurement, it is clear that, within decades after its toleration by Constantine, rather than centuries, Christianity had a predominant place in the religious life of the Roman world.

Further reading

The starting place, of course, is the New Testament. The four gospels and the Acts of the Apostles describe the life of Christ and the life of the early Christian community, while the epistles of early Christian leaders provide insight into the issues that concerned them and their flocks.

Of contemporary histories the most accessible is The History of the Church: From Christ to Constantine, published as a Penguin Classic (Harmondsworth, Mddsx, 1960, and frequently reprinted), by Eusebius (c.260–c.340), who suffered imprisonment, became a bishop and was a friend of Emperor Constantine. It sheds much light on the experiences of the early Christians. An accessible, comprehensive work is Henry Chadwick, The Church in Ancient Society: From Galilee to Gregory the Great (Oxford, 2001). For the early post-apostolic period one may consult W.A. Meeks, The First Urban Christians: The Social World of the Apostle Paul (New Haven and London, 1983), which adopts the approach of social history.

On persecutions one may begin with W.H.C. Frend, Martyrdom and Persecution in the Early Church (Oxford, 1965). A lively debate on the question can be found in the journal Past and Present, vols 26 (1963) and 27 (1964). Also, one should see P.S. Davies, ‘The Origin and Purpose of the Persecution of AD 303’, Journal of Theological Studies 40 (1989), 66–94. A volume concerned with that persecution is The Great Persecution (eds D. Vincent Twomey and Mark Humphries; Dublin, 2009); see particularly the article by Professor Humphries (pp. 11–32).

Ramsey MacMullen makes interesting observations about the spread of Christianity in Christianizing the Roman Empire (A.D. 100–400) (New Haven and London, 1984). J.N.D. Kelly provides a description of the theological developments in Early Christian Doctrine (5th edn; London, 1977) as does Jaroslav Pelikan in The Emergence of the Catholic Tradition, 100–600 (vol. 1 of The Christian Tradition: A History of the Development of Doctrine, Chicago and London, 1971). For a more specialized work see R.P.C. Hanson, The Search for the Christian Doctrine of God: The Arian Controversy, 318–381 (Edinburgh, 1988). Two works on St Augustine should be mentioned: Peter Brown, Augustine of Hippo: A Biography (new edn; London, 2000) and Serge Lancel, Saint Augustine (tr. Antonia Nevill; London, 2002).

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